Celebrity sex scandals have helped fuel mainstream demand for treatment of sex addiction, though it has yet to be officially acknowledged as a disorder and is not under government regulation.

When she hung out her shingle as a sex addiction therapist in 1997, Alexandra Katehakis had only a handful of colleagues.

"There were five people in this field and we all knew each other," she said.

These days, Katehakis, a licensed marriage and family therapist, has hundreds of competitors and has grown her Los Angeles solo practice into the Center for Healthy Sex, "a full-blown organization" with a team of counselors, an intensive outpatient program, a range of therapy groups, an expansive website and training for other therapists.

Celebrities have been the greatest evangelists for treatment. "My practice wouldn't exist without them," Katehakis said.

The for-profit field is booming, thanks largely to Tiger Woods and other celebrities whose public visits to rehab have moved sex addiction, a controversial diagnosis not recognized by the medical establishment, into the mainstream and led a growing number of Americans to conclude that they — or in many cases, their spouses — needed treatment.

A testament to the increasing demand for services and the potential money to be made providing them is the entrance into the sex addiction market this week of the private-equity-backed corporation that owns Promises, the high-end Malibu drug rehabilitation center known for its Hollywood clientele. The Cerritos company, Elements Behavioral Health, is buying a Westside treatment center, the Sexual Recovery Institute, as part of an expansion that will eventually include luxe in-patient facilities like Promises for wealthy sex addicts and a national network of two-week outpatient programs for those of lesser means.

The company has not disclosed the purchase price, but Chief Executive David Sack said Elements was making a significant investment on the belief that the Internet, with its easy access to pornography and casual liaisons, had created an epidemic of untreated sex addiction in America and that the rehab stays of Woods, actors Russell Brand and David Duchovny and others had informed a previously ignorant public about the existence of treatment programs.

"You have a backlog of people who need this treatment, and all of a sudden through a celebrity they have become aware that something can be done," said Sack, a psychiatrist.

Just how many people are seeking treatment is unclear. The rapid expansion of sex addiction programs, frequently described as "exponential" by those in the field, is occurring without the government regulation that exists in drug and alcohol treatment.

Public health agencies, insurance companies and others who compile data for other types of treatment do not monitor sex addiction because it is not listed in the Diagnostic and Statistical Manual of Mental Disorders, the American Psychiatric Assn.'s compendium of ailments.

Dr. Martin Kafka, a Boston-area psychiatrist and leader in the research of compulsive sexual behavior, said there was serious disagreement in the scientific community over whether humans could be addicted to sex in the same way they could be to alcohol or drugs. He said there was a lack of data demonstrating that sex addicts build up a tolerance over time or go through withdrawal if deprived of sex — two characteristics of substance addiction.

"That's not to say that in the next decade that there won't be … an empirical scientific backing for withdrawal and tolerance, but it's just not there now," Kafka said.

That's left it to the industry to define sex addiction, and it does so broadly. Sex addiction is "any sexually related, compulsive behavior which interferes with normal living and causes severe stress on family, friends, loved ones and one's work environment," according to a group that certifies sex therapists, the International Institute for Trauma and Addiction Professionals, or IITAP.

Some in the field estimate that 3% to 5% of Americans are sex addicts, while others say the proportion is probably greater.

The made-for-tabloid scandals around Woods and reality-TV star Jesse James, with their beautiful wronged wives and choruses of mistresses, prompted some pundits to dismiss sex addiction as a convenient recasting of run-of-the-mill infidelity. Therapists acknowledge that the threatened loss of a marriage, job or health is normally what prompts treatment, but they say someone who has had an affair or two would never be diagnosed as a sex addict.

"By the time they get here, they usually have hundreds of [sexual] contacts and years and years of a double life," said Rob Weiss, the founding director of the Sexual Recovery Institute, an outpatient center near Beverly Hills.

However sex addiction is defined, there is ample anecdotal evidence that more people think they have it. The number of sex therapists certified by the international institute has doubled — to about 900 — since 2007, and counselors say demand increases monthly.

Weiss said business at the Sexual Recovery Institute was up 50% from a year ago.